Single UNIX Specification

The Single UNIX Specification (SUS) is the collective name of a family of standards for computeroperating systems, compliance with which is required to qualify for the name "Unix". The core specifications of the SUS are developed and maintained by the Austin Group, which is a joint working group of IEEE, ISO JTC 1 SC22 and The Open Group.

Contents

History1

1980s: Motivation1.1

1988: POSIX1.2

1990s: Spec 11701.3

1997: Single UNIX Specification version 21.4

2001: POSIX:2001, Single UNIX Specification version 31.5

2004: POSIX:20041.6

2008: POSIX:20081.7

Specification2

Marks for compliant systems3

Compliance4

Registered UNIX systems4.1

AIX4.1.1

HP-UX4.1.2

Inspur K-UX4.1.3

OS X4.1.4

Reliant UNIX4.1.5

SCO4.1.6

Solaris4.1.7

Tru64 UNIX4.1.8

z/OS4.1.9

Other4.1.10

Non-registered Unix-like systems4.2

BSD descendants4.2.1

Linux4.2.2

See also5

Notes6

References7

External links8

History

1980s: Motivation

The SUS emerged from a mid-1980s project to standardize operating systeminterfaces for software designed for variants of the Unix operating system. The need for standardization arose because enterprises using computers wanted to be able to develop programs that could be used on the computer systems of different manufacturers without reimplementing the programs. Unix was selected as the basis for a standard system interface partly because it was manufacturer-neutral.

1988: POSIX

In 1988, these standards became IEEE 1003 (also registered as ISO/IEC 9945), or POSIX, which loosely stands for Portable Operating System Interface.

1990s: Spec 1170

In the early 1990s, a separate effort known as the Common API Specification or Spec 1170 was initiated by several major vendors, who formed the COSE alliance in the wake of the Unix wars. This specification became more popular because it was available at no cost, whereas the IEEE charged a substantial fee for access to the POSIX specification. Management over these specifications was assigned to X/Open who also received the Unix trademark from Novell in 1993. Unix International (UI) merged into Open Software Foundation (OSF) in 1994 only to merge with X/Open to form The Open Group in 1996.

1997: Single UNIX Specification version 2

In 1997, the Open Group released the Single UNIX Specification Version 2.[1][2]

This specification consisted of:

the Base Definitions, Issue 5,

the System Interfaces and Headers, Issue 5,

the Commands and Utilities, Issue 5,

the Networking Services, Issue 5,

the X/Open Curses, Issue 4, Version 2,

and was at the core of the UNIX 98 brand.[3]

2001: POSIX:2001, Single UNIX Specification version 3

Beginning in 1998, a joint working group known as the Austin Group began to develop the combined standard that would be known as the Single UNIX Specification Version 3 and as POSIX:2001 (formally: IEEE Std 1003.1-2001). It was released on January 30, 2002.[4]

This standard consisted of:

the Base Definitions, Issue 6,

the System Interfaces and Headers, Issue 6,

the Commands and Utilities, Issue 6,

and is at the core of the UNIX 03 brand.[5]

2004: POSIX:2004

In 2004, a new edition of the POSIX:2001 standard was released, incorporating two technical corrigenda. It is called POSIX:2004 (formally: IEEE Std 1003.1-2004).[6][7]

2008: POSIX:2008

In December 2008, the Austin Group published a new major revision, known as POSIX:2008 (formally: IEEE Std 1003.1-2008).[8][9][10] This is the core of the Single UNIX Specification, Version 4.[11]

This standard consists of:

the Base Definitions, Issue 7,

the System Interfaces and Headers, Issue 7,

the Commands and Utilities, Issue 7.

Specification

SUSv3 totals some 3700 pages, which are thematically divided into four main parts:

Base Definitions (XBD) - a list of definitions and conventions used in the specifications and a list of C header files which must be provided by compliant systems. 84 header files in total are provided.

Shell and Utilities (XCU) - a list of utilities and a description of the shell, sh. 160 utilities in total are specified.

System Interfaces (XSH) - contains the specification of various functions which are implemented as system calls or library functions. 1123 system interfaces in total are specified.

Rationale (XRAT) - the explanation behind the standard.

The standard user command line and scripting interface is the POSIX shell, an extension of the Bourne Shell based on an early version of the Korn Shell. Other user-level programs, services and utilities include awk, echo, ed, vi, and hundreds of others. Required program-level services include basic I/O (file, terminal, and network) services. A test suite accompanies the standard. It is called PCTS or the POSIX Certification Test Suite.

Reliant UNIX

SCO

Solaris

Solaris 11 complies with the Single UNIX Specification.[19] Solaris 10 is registered as UNIX 03 compliant on 32-bit and 64-bitx86 (X86-64) and SPARC systems. Solaris 8 and 9 are registered as UNIX 98 compliant on 32-bitx86 and SPARC systems; 64-bit x86 systems are not supported.

Solaris 2.5.1 was also registered as UNIX 95 compliant on the PRePPowerPC platform in 1996, but the product was withdrawn before more than a few dozen copies had been sold.[20]

Other

Non-registered Unix-like systems

Vendors of Unix-like systems such as Linux and FreeBSD do not typically certify their distributions, as the cost of certification and the rapidly changing nature of such distributions make the process too expensive to sustain.[23]

BSD descendants

FreeBSD has a "C99 and POSIX Conformance Project"[24] which aims for full compliance with a large subset of the SUS.

Darwin is an open source operating system: it is essentially the open source subset of Mac OS X. Darwin is compliant with the SUS 03.[25]

Linux

Linux aims to be compliant, but as certification is expensive, no Linux distribution has been registered as SUS compliant.[26]

The Linux Standard Base was formed in 2001 as an attempt to standardize the internal structures of Linux-based systems for increased compatibility. It is based on, and also extends in several areas, the POSIX specifications, the Single UNIX Specification and other open standards. It is de facto accepted and followed by many Linux distributions.

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